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Purpose: T cells influence outcome in follicular lymphoma, but their contributions seem to be modified by therapy. Their impact in patients receiving rituximab without chemotherapy is unknown.Experimental Design: Using flow cytometry, we evaluated the T cells in tumors and/or blood in a total of 250 follicular lymphoma patients included in two Nordic Lymphoma Group randomized trials that compared single rituximab with IFN-α2a–rituximab combinations.Results: In univariate analysis, higher levels of CD3+, CD4+, and CD8+ T cells in both tumors and blood correlated with superior treatment responses, and in multivariate analysis, tumor-CD3+ (P = 0.011) and blood-CD4+ (P = 0.029) cells were independent. CD4+ cells were favorable regardless of treatment arm, but CD8+ cells were favorable only in patients treated with single rituximab, because IFN-α2a improved responses especially in patients with low CD8+ cell levels. Higher levels of blood-CD3+ (P = 0.003) and blood-CD4+ (P = 0.046) cells predicted longer overall survival, and higher levels of blood-CD8+ cells longer times to next treatment (P = 0.046).Conclusions: We conclude that therapeutic effects of rituximab are augmented by tumor-associated T cells for rapid responses and by systemic T cells for sustained responses. CD4+ and CD8+ cells are both favorable in patients treated with rituximab. IFN-α2a abrogates the negative impact of few CD8+ cells. Clin Cancer Res; 17(12); 4136–44. ©2011 AACR.

Supplementary Materials and Methods from T Cells in Tumors and Blood Predict Outcome in Follicular Lymphoma Treated with Rituximab

Despite improvement of current treatment strategies and novel targeted drugs, relapse and treatment resistance largely determine the outcome for acute myeloid leukemia (AML) patients. To identify the underlying molecular characteristics, numerous studies have been aimed to decipher the genomic- and transcriptomic landscape of AML. Nevertheless, further molecular changes allowing malignant cells to escape treatment remain to be elucidated. Mass spectrometry is a powerful tool enabling detailed insights into proteomic changes that could explain AML relapse and resistance. Here, we investigated AML samples from 47 adult and 22 pediatric patients at serial time-points during disease progression using mass spectrometry-based in-depth proteomics. We show that the proteomic profile at relapse is enriched for mitochondrial ribosomal proteins and subunits of the respiratory chain complex, indicative of reprogrammed energy metabolism from diagnosis to relapse. Further, higher levels of granzymes and lower levels of the anti-inflammatory protein CR1/CD35 suggest an inflammatory signature promoting disease progression. Finally, through a proteogenomic approach, we detected novel peptides, which present a promising repertoire in the search for biomarkers and tumor-specific druggable targets. Altogether, this study highlights the importance of proteomic studies in holistic approaches to improve treatment and survival of AML patients. Title in the list of papers of Svea Stratmann thesis: Proteogenomic analysis of relapsed acute myeloid leukemia in adults and childrenAuthors in the list of papers of Svea Stramann: S. Stratmann, M. Vesterlund, H.M. Umer, A. Skaftason, M. Krogh Herlin, C. Sundström, A. Eriksson, M. Höglund, J. Palle, J. Abrahamson, K. Jahnukainen, M. Cheng Munthe-Kaas, B. Zeller, K. Pokrovskaja Tamm, L. Cavelier, J. Lehtiö, L. Holmfeld

Background: Treatment with antithymocyte globulin (ATG) is a well-recognized risk factor for the development of post-transplant lymphoproliferative disorders (PTLD) after solid organ transplantation, but it is unknown how its use affects overall survival after PTLD. Methods: A total of 114 patients with PTLD and available data on immunosuppressive regimen were included from a nation-wide case series of solid organ transplant recipients in Sweden. Prior use of ATG was correlated to clinical features, PTLD subtype, and survival. Results: A total of 47 (41%) patients had received ATG prior to the diagnosis of PTLD. The ATG-treated patients were more likely to be recipients of hearts or lungs, and less likely of kidneys (p < 0.01). They had experienced more acute rejections (p = 0.02). The PTLDs arose earlier, median 2.0 vs. 6.6 years post-transplant (p = 0.002) and were more often situated in the allograft (32% vs. 7%, p < 0.001) in patients with prior ATG vs. no ATG treatment. The PTLDs in the ATG group were more often Epstein-Barr virus-positive (80% vs. 40%, p < 0.001). There were more polymorphic PTLDs (17% vs. 1.5%, p = 0.004) and less T-cell PTLDs (4% vs. 19%, p = 0.02) in the ATG group than in the no ATG group. Diffuse large B-cell lymphoma was equally common in patients with and without prior ATG therapy, but the non-germinal center subtype was more frequent in the ATG group (p = 0.001). In an adjusted Cox proportional hazards regression model, prior ATG treatment and better performance status were associated with superior overall survival, whereas older age, T-cell subtype of PTLD, presence of B symptoms, and elevated lactate dehydrogenase were associated with inferior overall survival. Patients receiving ATG solely as rejection therapy had superior overall survival compared with those receiving ATG as induction therapy or both (p = 0.03). Conclusions: ATG therapy, especially rejection therapy, prior to PTLD development is an independent prognostic factor for superior overall survival after PTLD diagnosis.

Outcome in PCNSL patients and its association with PD-L1+ leukocytes in the tumor microenvironment

Objectives To estimate the association between biological DMARDs (bDMARDs; overall and by drug) as used in RA and the risk of malignant lymphomas including subtypes. Methods By linking nationwide Swedish registers we identified cohorts of patients with RA initiating treatment with a bDMARD (n = 16 392), bDMARD-naïve (n = 55 253), an age- and sex-matched general population comparator cohort (n = 229 047), and all incident lymphomas 2001–16. We used Cox regression to calculate hazard ratios (HRs) of lymphoma taking calendar period and other factors into account. Results There were 82 lymphomas among the bDMARD-treated patients with RA, crude incidence rate 76/100 000 person-years, and 310 lymphomas among the bDMARD-naïve patients with RA, crude incidence rate 90/100 000 person-years. This resulted in an adjusted HR (aHR) associated with bDMARD treatment (vs not) of 1.08 (95% CI: 0.83, 1.41). The corresponding aHR for bDMARD-treated and bDMARD-naïve vs the general population was 1.65 (95% CI: 1.31, 2.08) and 1.56 (95% CI: 1.37, 1.78) respectively. Restricting follow-up period to after 2006, the aHR of lymphoma for patients with RA starting a first bDMARD vs bDMARD-naïve was 0.69 (95% CI: 0.47, 1.00), and for bDMARD treated vs patients with RA switching from one conventional synthetic DMARDs to another, aHR was 0.46 (95% CI: 0.28, 0.73). There were no signals of different risks with any particular TNF inhibitor (TNFi) agent. We found no different lymphoma subtype pattern following bDMARD therapy. Conclusion Treatment with bDMARDs, including both TNFi and non-TNFi bDMARDs, does not further increase the lymphoma risk in RA; instead, bDMARD treatment may actually reduce the excess lymphoma risk in RA.

Survival for patients diagnosed with mantle cell lymphoma (MCL) has improved drastically in recent years. However, patients carrying mutations in tumour protein p53 (TP53) do not benefit from modern chemotherapy-based treatments and have poor prognosis. Thus, there is a clinical need to identify missense mutations through routine analysis to enable patient stratification. Sequencing is not widely implemented in clinical practice for MCL, and immunohistochemistry (IHC) is a feasible alternative to identify high-risk patients. The aim of the present study was to investigate the accuracy of p53 as a tool to identify patients withTP53missense mutations and the prognostic impact of overexpression and mutations in a Swedish population-based cohort. In total, 317 cases were investigated using IHC and 255 cases were sequenced, enabling analysis of p53 andTP53status among 137 cases divided over the two-cohort investigated. The accuracy of predicting missense mutations from protein expression was 82%, with sensitivity at 82% and specificity at 100% in paired samples. We further show the impact of p53 expression andTP53mutations on survival (hazard ratio of 3 center dot 1 in univariate analysis for both), and the association to risk factors, such as high MCL International Prognostic Index, blastoid morphology and proliferation, in a population-based setting.

Simple Summary Immunotherapy blocking programmed cell death protein 1 (PD-1) and its ligands (PD-L1, PD-L2) is less effective in non-Hodgkin lymphoma (NHL) than classical Hodgkin lymphoma. However, NHL is a heterogeneous group and current research seeks to identify subgroups of NHL patients responsive to PD-1 blocking agents. Whether patients with pre-existing rheumatic diseases might constitute such a subgroup is unknown. We investigated the expression of PD-1 and its ligands in lymphoma patients with pre-existing rheumatic diseases. Our key findings include that in patients with pre-existing rheumatoid arthritis (RA) and subsequent diffuse large B-cell lymphoma, an association between RA disease severity and increased expression of PD-L1 in tumor cells was seen. This warrants further studies of the PD-1 pathway in lymphoma in other chronic inflammatory conditions. Current research seeks to identify subgroups of non-Hodgkin lymphoma (NHL) patients responsive to PD-1 blocking agents. Whether patients with pre-existing rheumatic diseases might constitute such a subgroup is unknown. We determined intratumoral expression of PD-1 and its ligands in lymphoma patients with pre-existing rheumatic diseases. We included 215 patients with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) or Sjogren's syndrome with subsequent lymphoma and 74 diffuse large B-cell lymphoma (DLBCL) controls without rheumatic disease. PD-1 and PD-ligand immunohistochemical markers were applied on tumor tissue microarrays. The number of PD-1+ tumor infiltrating leukocytes (TILs) and proportions of PD-L1+ and PD-L2+ tumor cells and TILs were calculated and correlated with clinical data. Expression of PD-L1 in tumor cells and TILs was highest in classical Hodgkin lymphoma and DLBCL. In DLBCLs, expression of PD-1 in TILs and PD-L1 in tumor cells was similar in RA, SLE and controls. In RA-DLBCL, high expression of PD-L1 in tumor cells was significantly more common in patients with the most severe RA disease and was associated with inferior overall survival in multivariable analysis.

BCOR is a component of a variant Polycomb repressive complex 1 (PRC1.1). PRC1 and PRC2 complexes together constitute a major gene regulatory system critical for appropriate cellular differentiation. The gene is upregulated in germinal center (GC) B cells and mutated in a number of hematologic malignancies. We report

Background Programmed cell death 1 (PD-1) and its ligands PD-L1 and PD-L2, as well as Indoleamine 2,3-deoxygenase (IDO1) can be expressed both by tumor and microenvironmental cells and are crucial for tumor immune escape. We aimed to evaluate the role of PD-1, its ligands and IDO1 in a cohort of patients with primary diffuse large B-cell lymphoma of the CNS (PCNSL). Material and methods Tissue microarrays (TMAs) were constructed in 45 PCNSL cases. RNA extraction from whole tissue sections and RNA sequencing were successfully performed in 33 cases. Immunohistochemical stainings for PD-1, PD-L1/paired box protein 5 (PAX-5), PD-L2/PAX-5 and IDO1, and Epstein-Barr virus encoding RNA (EBER) in situ hybridization were analyzed. Results High proportions of PD-L1 and PD-L2 positive tumor cells were observed in 11% and 9% of cases, respectively. High proportions of PD-L1 and PD-L2 positive leukocytes were observed in 55% and 51% of cases, respectively. RNA sequencing revealed that gene expression of IDO1 was high in patients with high proportion of PD-L1 positive leukocytes (p = .01). Protein expression of IDO1 in leukocytes was detected in 14/45 cases, in 79% of these cases a high proportion of PD-L1 positive leukocytes was observed. Gene expression of IDO1 was high in EBER-positive cases (p = .0009) and protein expression of IDO1 was detected in five of six EBER-positive cases. Conclusion Our study shows a significant association between gene and protein expression of IDO1 and protein expression of PD-L1 in the tumor microenvironment of PCNSL, possibly of importance for prediction of response to immunotherapies. Title in Thesis: PD-L1 and IDO1 are important immunosuppressive molecules in primary diffuse large B-cell lymphoma of the CNS

Patients with autoimmune diseases (AD) have an increased risk to develop benign lymphadenopathies compared to patients without AD. The aim with this study was to determine the role of the PD-1 pathway and the number of cells harboring Epstein-Barr virus (EBV) in benign lymphadenopathies in patients with AD (cases) compared to patients without AD (controls). Pathology registries were screened to identify patients with biopsies diagnosed as benign lymphadenopathy and medical journals were reviewed for information on AD. Immunohistochemical stainings (PD-1 and PD-L1) and EBER in situ hybridization for EBV were applied on lymph node biopsies in patients with AD (n = 22) and patients without AD (n = 57). The case group was compared with the control group with Wilcoxon-signed rank, chi-square and Fischeŕs exact test. There was a statistically significantly higher proportion of PD-1+ cells and a tendency for a lower prevalence of PD-L1+ and EBV+ cells in cases compared to controls. Apparently, patients with AD have an altered immune response as revealed in benign lymphadenopathies compared to patients without AD. If this association might be a piece of the puzzle for the increased risk of development of lymphomas in patients with AD remains to be determined.

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) is a rare lymphoma of B-cell origin with frequent expression of functional B-cell receptors (BCRs). Here we report that expression cloning followed by antigen screening identifies DNA-directed RNA polymerase beta’ (RpoC) from Moraxella catarrhalis as frequent antigen of BCRs of IgD+ LP cells. Patients show predominance of HLA-DRB1*04/07 and the IgVH genes encode extraordinarily long CDR3s. High-titer, light-chain-restricted anti-RpoC IgG1/κ-type serum-antibodies are additionally found in these patients. RpoC and MID/hag, a superantigen co-expressed by Moraxella catarrhalis that is known to activate IgD+ B cells by binding to the Fc domain of IgD, have additive activation effects on the BCR, the NF-κB pathway and the proliferation of IgD+ DEV cells expressing RpoC-specific BCRs. This suggests an additive antigenic and superantigenic stimulation of B cells with RpoC-specific IgD+ BCRs under conditions of a permissive MHC-II haplotype as a model of NLPHL lymphomagenesis, implying future treatment strategies., Nodular lymphocyte-predominant Hodgkin lymphoma with IgD+ lymphocyte-predominant (LP) cells is a rare clinical distinct lymphoma subset of B-cell origin. Here the authors show that antigens expressed by Moraxella catarrhalis are recognized by B cell receptors of IgD+ LP cells, suggesting the contribution of chronic antigen stimulation to lymphomagenesis.

Background: Post-transplant lymphoproliferative disorder (PTLD) is a rare but life-threatening complication of transplantation. For refractory and relapsed PTLD new therapies are needed, such as the antibody-drug conjugate brentuximab vedotin that targets CD30. There is limited knowledge of CD30 expression in various subtypes of PTLD and its correlation to clinicopathological features. Therefore, we studied the expression of CD30 in PTLD following solid organ transplantation and correlated CD30 expression to PTLD subtype, Epstein-Barr virus (EBV)-status, intratumoral regulatory T-cells (Tregs), clinical features, and outcome. Methods: We included 50 cases of PTLD from a nation-wide study of PTLDs following solid organ transplantation in Sweden. The tumor biopsies were reevaluated, and clinical data were collected. CD30 expression on tumor cells was analyzed by immunohistochemistry with the clone Ber-H2. Thirty-one cases were stained with clone 236 A/E7 for detection of forkhead box protein 3 (FoxP3, a Treg biomarker). Results: The case series consisted of 6% polymorphic, 88% monomorphic, and 6% Hodgkin lymphoma-like PTLDs and 53% of the cases were EBV+. Overall, 70% (35/50) of the PTLDs were CD30+ (>= 1% CD30+ tumor cells) and 30% (15/50) were CD30-. All polymorphic PTLDs (n = 3) and Hodgkin lymphomas (n = 3), 88% (14/16) of non-germinal center type of diffuse large B-cell lymphoma (DLBCL), and 75% (9/12) of T-cell PTLDs were CD30+ whereas all germinal center-type of DLBCL (n = 5) and Burkitt type PTLD (n = 2) were CD30-. CD30+ PTLD tended to be EBV+ more frequently (p = .07) and occurred earlier posttransplant (2.1 vs. 8.2 years, p = .01) than CD30- PTLD. Type of transplant and localization of the tumor did not differ between the groups except that CNS engagement was more common in CD30- PTLD (p = .02). CD30-status was not associated with presence of intratumoral Tregs or overall survival. Conclusion: Expression of CD30 varied with PTLD subtype. There was no association between CD30 and survival, regardless of subtype.

To obtain insight into the ontogeny of mantle cell lymphoma (MCL), we assessed 206 patients from a morphological, immunohistochemical, and immunogenetic perspective. Our series included nodal ( n = 151), extranodal ( n = 28), and primary splenic ( n = 27) MCL cases. Skewing of the immunoglobulin heavy variable (IGHV) gene repertoire was noted, with only four IGHV genes accounting for 46% of cases and approximately 70% of cases (107/154) bearing an imprint of somatic hypermutation (SHM) ranging from minimal to pronounced. Interestingly, a distinctive immunophenotypic and immunogenetic profile was identified for primary splenic MCL, which was enriched for DBA.44-positive cases ( P P = 0.02) compared to nodal or extranodal cases, alluding to distinct immunopathogenetic and antigen selection processes. Expression of CD27 (considered a marker of activated B cells) was generally dissociated from SHM and was more prevalent in cases with no or minimal/borderline SHM. These findings support the idea that antigen drive is relevant for most MCL cases, although the specific antigens and the precise location of affinity maturation remain to be elucidated. Moreover, they raise the intriguing hypothesis of multiple cellular origins for MCL.

Angioimmunoblastic T-cell lymphomas (AITLs) frequently carry mutations in the TET2 and IDH2 genes. TET2 mutations represent early genetic lesions as they had already been detected in haematopoietic precursor cells of AITL patients. We show by analysis of whole-tissue sections and microdissected PD1+ cells that the frequency of TET2-mutated AITL is presumably even higher than reported (12/13 cases in our collection; 92%). In two-thirds of informative AITLs (6/9), a fraction of B cells was also TET2-mutated. Investigation of four AITLs by TET2 and IGHV gene sequencing of single microdissected B cells showed that between 10% and 60% of polyclonal B cells in AITL lymph nodes harboured the identical TET2 mutations of the respective T-cell lymphoma clone. Thus, TET2-mutated haematopoietic precursor cells in AITL patients not only give rise to the T-cell lymphoma but also generate a large population of mutated mature B cells. Future studies will show whether this is a reason why AITL patients frequently also develop B-cell lymphomas. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Follicular lymphoma (FL) constitutes a significant proportion of lymphomas and shows frequent relapses. Beyond conventional chemotherapy, new therapeutic approaches have emerged, focussing on the interplay between lymphoma cells and the microenvironment. Here we report the immunophenotypic investigation of the microenvironment of a clinically well-characterized prospective cohort (study SAKK35/10, NCT01307605) of 154 treatment-naive FL patients in need of therapy, who have been treated with rituximab only or a combination of rituximab and the immunomodulatory drug lenalidomide/Revlimid® A high ratio of CD4- to CD8-positive T cells (P = 0·009) and increased amounts of PD1+ tumour-infiltrating T cells (P = 0·007) were associated with inferior progression-free survival in the whole cohort. Interestingly, the prognostic impact of PD1+ T cells and the CD4/CD8 ratio lost its significance in the subgroup treated with R2 . In the latter group, high amounts of GATA3+ T helper (Th2) equivalents were associated with better progression-free survival (P < 0·001). We identified tumour microenvironmental features that allow prognostic stratification with respect to immuno- and combined immuno- and immunomodulatory therapy. Our analysis indicates that lenalidomide may compensate the adverse prognostic implication of higher amounts of CD4+ and, particularly, PD1+ T cells and that it has favourable effects mainly in cases with higher amounts of Th2 equivalents. [Correction added on 11 February 2020, after online publication: The NCT-trial number was previously incorrect and has been updated in this version].

Several autoimmune and inflammatory conditions, such as rheumatoid arthritis (RA) and primary Sjogrens’s syndrome (pSS), have repeatedly been linked to an increased risk of malignant lymphoma [1,2]...

We studied the expression of programed death 1 (PD-1) receptor and its ligands (PD-L1/-L2) by immunohistochemistry and its association with clinicopathological features in 81 posttransplant lymphoproliferative disorders (PTLDs) following solid organ transplantation. Overall, 67% (54/81) of the PTLDs were positive in any of the three immunostainings. PD-1 was detected on tumor-infiltrating cells in 41% (33/81) of the PTLDs. PD-L1 was expressed on ≥5% of the tumor cells in 50% (40/80) and PD-L2 in 32% (23/72) of the PTLDs. All Burkitt lymphomas were PD-L1 negative. Expression of PD-L1 tended to be associated with non-germinal center-type of diffuse large B-cell lymphoma (63% vs. 33% in GC-type, p = .14) and latent membrane protein-1+ PTLD (76% vs. 44% in LPM1-, p = .09). Heart recipients had more frequent PTLDs with PD-1+ microenvironment (p = .01). The frequent expression of PD-1 or -L1/-L2 in PTLD warrants further clinical evaluation of the efficacy and safety of PD-(L)1 inhibitors for refractory PTLD.

Objective: In the 2016 American College of Rheumatology/European League Against Rheumatism classification criteria for primary Sjogren’s syndrome (pSS), pre-existing lymphoma is not an exclusion criterion for pSS diagnosis, as in earlier criteria. We aimed to explore whether there are differences between pSS patients with and without pre-existing lymphoma at pSS diagnosis. Method: Patients with ICD-7–10 codes for Sjogren’s syndrome (SS) and a diagnosis of malignant lymphoma before or after SS diagnosis were identified by linking the Swedish Patient Register 1964–2007 with the Cancer Register 1990–2007 (n = 224). Clinical data were collected from medical records. Lymphoma diagnoses were evaluated by tissue review. Characteristics of pSS patients with and without pre-existing lymphoma were compared. Results: We identified 107 patients with pSS as the reason for an SS diagnosis code and a verified lymphoma. Of these, 18 (17%) had a pre-existing lymphoma at pSS diagnosis, defined as lymphoma diagnosed before or within 6 months of pSS diagnosis. Male gender (39% vs 10%, p = 0.006), enlarged lymph nodes during the pSS disease (61% vs 27%, p = 0.01), mucosa-associated lymphoid tissue (MALT) lymphoma (50% vs 22%, p = 0.02), and salivary gland lymphoma (61% vs 26%, p = 0.006) were more common in patients with a pre-existing lymphoma at pSS diagnosis. Other pSS characteristics were similar. Conclusion: In a substantial proportion of patients, particularly in men, pSS remains undiagnosed until after lymphoma diagnosis. The study highlights the importance of pSS investigation in patients with lymphoma, especially MALT lymphoma, in the salivary glands. (Less)

Objectives Investigating expression of possible targets for proteasome inhibitors in patients with diffuse large B-cell lymphoma (DLBCL) and correlating the findings to clinical parameters and outcome. Methods Tumour material from 92 patients with DLBCL treated with either R-CHOP like (n = 69) or CHOP like (n = 23) regimens were stained for possible targets of proteasome inhibitors. Results The primary target molecule of bortezomib, proteasome subunit beta, type 5 (PSMB5), was not detected in the tumour cells in any of the cases but showed an abundant expression in cells in the microenvironment. However, the deubiquitinases (DUBs) of the proteasome, the ubiquitin carboxyl-terminal hydrolase L5 (UCHL5) and the ubiquitin specific peptidase 14 (USP14), were detected in the cytoplasm of the tumour cells in 77% and 74% of the cases, respectively. The adhesion regulating molecule 1 (ADRM1) was detected in 98% of the cases. There was no correlation between the expression of any of the studied markers and clinical outcome or GC/non-GC phenotype. Conclusions We suggest that UCHL5 and/or USP14 should be further evaluated as new targets for proteasome inhibitors in DLBCL. The lack of expression of PSMB5 on the tumour cells might provide an explanation of the relatively poor results of bortezomib in DLBCL.

Primary mediastinal B-cell lymphoma (PMBL) is an entity of B-cell lymphoma distinct from the other molecular subtypes of diffuse large B-cell lymphoma (DLBCL). We investigated the prevalence, specificity, and clinical relevance of mutations of XPO1, which encodes a member of the karyopherin-β nuclear transporters, in a large cohort of PMBL. PMBL cases defined histologically or by gene expression profiling (GEP) were sequenced and the XPO1 mutational status was correlated to genetic and clinical characteristics. The XPO1 mutational status was also assessed in DLBCL, Hodgkin lymphoma (HL) and mediastinal gray-zone lymphoma (MGZL).The biological impact of the mutation on Selective Inhibitor of Nuclear Export (SINE) compounds (KPT-185/330) sensitivity was investigated in vitro. XPO1 mutations were present in 28/117 (24%) PMBL cases and in 5/19 (26%) HL cases but absent/rare in MGZL (0/20) or DLBCL (3/197). A higher prevalence (50%) of the recurrent codon 571 variant (p.E571K) was observed in GEP-defined PMBL and was associated with shorter PFS. Age, International Prognostic Index and bulky mass were similar in XPO1 mutant and wild-type cases. KPT-185 induced a dose-dependent decrease in cell proliferation and increased cell-death in PMBL cell lines harboring wild type or XPO1 E571K mutant alleles. Experiments in transfected U2OS cells further confirmed that the XPO1 E571K mutation does not have a drastic impact on KPT-330 binding. To conclude the XPO1 E571K mutation represents a genetic hallmark of the PMBL subtype and serves as a new relevant PMBL biomarker. SINE compounds appear active for both mutated and wild-type protein.

The susceptibility to Epstein-Barr virus (EBV)-related post-transplant lymphoproliferative disorder (PTLD) may be affected by the human leukocyte antigen (HLA) type. We investigated HLA-A and HLA-B allele frequencies, focusing on HLA-A1 and -A2, in a population-based case series of EBV + (n = 60) and EBV- (n = 44) PTLD after solid organ transplantation. The proportion of EBV + PTLD was highest in HLA-A1 homozygotes (100%), lower in carriers of HLA-A1/AX (79%), HLA-A1/A2 (55%), HLA-A2/AX (54%), and lowest in HLA-A2 homozygotes (37%). HLA-A1 type was overrepresented (22% versus 7%, p = 0.05) and HLA-A2 type underrepresented (57% versus 80%, p = 0.01) in patients with EBV + compared with EBV - PTLD. EBV + PTLD in HLA-A1 carriers developed almost exclusively in already EBV-seropositive individuals. EBV status of PTLD was not related to any other HLA-A or HLA-B type. Our findings suggest that HLA-A1 carriers may have an increased risk of EBV + PTLD due to a decreased ability to control the latent EBV infection.

Plasma cells are important prognostic actors in different malignancies. The tumour microenvironmental composition in classic Hodgkin lymphoma (cHL) is a major prognostic key element; however, clinicopathological studies regarding plasma cells in cHL are lacking. The aim of this study was to investigate CD138+ (also termed SDC1+) plasma cell and IgG4 producing (IgG4+) plasma cells infiltration in the microenvironment of cHL. Immunohistochemistry with anti-CD138 and IgG4 antibodies was performed on diagnostic tumour biopsies from 124 patients with cHL, on tissue micro array (TMA). In 120 cases, CD138+ plasma cell-infiltration was associated with the presence of B-symptoms (P = 0·028) and advanced stage, IIB-IVB (P = 0·009). In multivariate analysis, CD138+ plasma cells correlated with eosinophil infiltration (P = 0·013). The subgroup of IgG4+ plasma cells was analysed in 122 cases and only correlated to CD138+ plasma cells (P = 0·004). Patients with high proportion of tumour infiltrating CD138+ plasma cells (defined as ≥10%), had a more inferior event-free survival (P = 0·007) and overall survival (P = 0·004) than patients with a low proportion of infiltrating CD138+ plasma cells (

Immune evasion plays a central role in the pathophysiology of classical Hodgkin lymphoma (cHL). As mutations of the CD58 gene contribute to immune evasion of diffuse large B cell lymphoma tumor cells, we studied whether alterations of the CD58 gene also occur in Hodgkin and Reed/Sternberg (HRS) cells of cHL. Single nucleotide polymorphism chip analysis revealed homozygous deletions within the CD58 gene in two cHL cell lines (SUP-HD1 and U-HO1). Sequencing of the CD58 gene in seven cHL cell lines disclosed in addition a homozygous splice site mutation in cell line KM-H2. None of the three mutated lines expressed CD58 protein on their surface. Thus, three of seven cHL cell lines analyzed harbor destructive CD58 mutations. Molecular analysis of isolated HRS cells from 10 primary cases of cHL; however, did not reveal any case with a CD58 mutation. A FICTION study indicated heterozygous deletions of CD58 in 3 of 13 cHL analyzed. Overall, we report frequent inactivating mutations of CD58 in cHL cell lines, but their rare occurrence in primary HRS cells. As the three cHL cell lines with CD58 mutations were all established from HRS cells located in pleural effusions, i.e., outside the normal lymph node microenvironment, in end-stages of the disease, CD58 inactivation in cHL might be predominantly prevalent to such situations.

The infiltration of regulatory T cells (Tregs) in lymphomas is associated with better prognosis for some types of lymphomas, but knowledge of their role in posttransplant lymphoproliferative disorders (PTLDs) is limited. We therefore investigated the association between the expression of the Treg marker forkhead box protein 3 (FoxP3) in biopsies of PTLDs and survival, PTLD subtype, and clinical characteristics.Seventy-four cases of PTLD after solid organ transplantation with sufficient material for further analysis were included from a population-based study of PTLDs in Sweden. The PTLD biopsies were reevaluated and stained with the 236A/E7 antibody to detect FoxP3 in lymphoma tissue. Detailed clinical data were collected retrospectively from medical records.Based on a cutoff level of 29 FoxP3 cells per mm, most (80%) of the PTLDs were FoxP3. Forty-seven of 74 PTLDs displayed no FoxP3 cells at all. The frequency of FoxP3 cells did not influence median overall survival. The FoxP3 PTLDs were more frequently of T-cell phenotype (P = 0.04), located at the graft (P = 0.03), occurred earlier after transplantation (P = 0.04), were more likely to develop in lung recipients (P = 0.04), and in patients that had received anti-T-cell globulin as induction therapy (P = 0.02). The FoxP3 PTLDs were associated with hepatitis C seropositivity (P = 0.03). In multivariate analysis, B-cell PTLD and hepatitis C infection were independent predictors of FoxP3 positivity.Our findings suggest that intratumoral FoxP3 Tregs do not influence survival in patients with PTLD. FoxP3 Tregs are rare in PTLD, possibly because of heavy immunosuppression.

Recent studies show that mantle cell lymphoma (MCL) express aberrant microRNA (miRNA) profiles; however, the clinical effect of miRNA expression has not previously been examined and validated in large prospective homogenously treated cohorts. We performed genome-wide miRNA microarray profiling of 74 diagnostic MCL samples from the Nordic MCL2 trial (screening cohort). Prognostic miRNAs were validated in diagnostic MCL samples from 94 patients of the independent Nordic MCL3 trial (validation cohort). Three miRNAs (miR-18b, miR-92a, and miR-378d) were significantly differentially expressed in patients who died of MCL in both cohorts. MiR-18b was superior to miR-92a and miR-378d in predicting high risk. Thus, we generated a new biological MCL International Prognostic Index (MIPI-B)-miR prognosticator, combining expression levels of miR-18b with MIPI-B data. Compared to the MIPI-B, this prognosticator improved identification of high-risk patients with regard to cause-specific, overall, and progression-free survival. Transfection of 2 MCL cell lines with miR-18b decreased their proliferation rate without inducing apoptosis, suggesting that miR-18b may render MCL cells resistant to chemotherapy by decelerating cell proliferation. We conclude that overexpression of miR-18b identifies patients with poor prognosis in 2 large prospective MCL cohorts and adds prognostic information to the MIPI-B. MiR-18b may reduce the proliferation rate of MCL cells as a mechanism of chemoresistance.

Objective.Previous studies have shown that patients with granulomatosis with polyangiitis (GPA) have an increased risk of hematological malignancies, especially leukemia. Our aim was to assess clinical characteristics and treatment of patients with GPA complicated by hematological malignancies with focus on leukemia and to describe these malignancies in more detail.Methods.From the Swedish population-based patient register, all individuals with a diagnosis of GPA from 1964–2012 were identified (n = 3224). Through linkage with the Swedish Cancer Register, we searched for all cases of leukemia [International Classification of Diseases (ICD) 7: 204–207 and corresponding codes ICD 8–10] registered after the first discharge listing GPA. The GPA diagnosis was evaluated using the European Medical Association classification algorithm. To confirm the hematological malignancy, all diagnostic bone marrow samples were reclassified. Clinical data of both the GPA and hematological malignancy were collected from medical files.Results.Twenty-one cases were identified, all of myeloid origin, including 9 with myelodysplastic syndrome developing to acute myeloid leukemia (MDS-AML), 7 AML, 3 MDS, and 2 chronic myeloid leukemia. The median time from GPA diagnosis to hematological malignancy was 8 years (range 5–21). All patients had severe generalized GPA and had received high doses of cyclophosphamide (CYC; median cumulative dose 96.5 g). Cytopenia occurred in 76% of the patients prior to the hematological malignancy.Conclusion.The findings emphasize the longterm risk of leukemia and MDS in CYC-treated, severely ill patients with GPA. Cytopenia during the course of GPA may be a warning sign and warrants a liberal attitude toward bone marrow examination.

Core needle biopsies for lymphoma diagnosis seriously affect diagnostics, treatment development and research Core needle biopsies (CNBs) are widely used in clinical diagnostic labs to aid in the diagnosis of malignant lymphomas and in latter years their use is increasing. CNBs provide a rapid method for obtaining tumour material and may be beneficial when the affected lymph nodes are located deep in the abdominal cavity or mediastinum and surgical excisional biopsies may be difficult to perform. However, according to the Swedish Haematopathology Quality and Standardization Committee, CNBs are insufficient for lymphoma diagnostic purposes and the guidelines state that material from surgical excisional biopsies are mandatory in order to obtain a robust histopathological evaluation of the lymph node architecture, cellular composition and growth pattern. Surgical excision biopsies also ensure that adequate material is available if additional molecular analyses should be required and also to facilitate future research.

Objective. Data on lymphoma risk in ankylosing spondylitis (AS) and psoriatic arthritis (PsA) are scarce. This study was undertaken to assess the risk of lymphoma in AS and PsA overall and in relat ...

A common treatment for follicular lymphoma is rituximab monotherapy. To identify patients for whom this regimen is adequate as first-line therapy, we applied the World Health Organization (WHO) classification for grading follicular lymphoma in a prospective central pathology review of the biopsies of previously untreated patients in two randomized trials of rituximab without chemotherapy. In the first trial (n₁ = 53), higher WHO grades correlated with longer time to next treatment, independently of clinical prognostic factors (p = 0.030); the finding was replicated in the second trial (n₂ = 221; p = 0.019). Higher grades were associated with better treatment responses (p = 0.018). Furthermore, also grades externally confirmed by independent local pathologists correlated with time to next treatment (p = 0.048). Flow cytometry in a separate patient series showed that the intensity of CD20 increased with the malignant cell size (p0.00005). In conclusion, WHO grade 1 follicular lymphoma correlates with inferior outcome after rituximab monotherapy. WHO grading might provide a clinically useful tool for personalized therapy.

Angioimmunoblastic T-cell lymphomas (AITLs) frequently carry mutations in the TET2 and IDH2 genes. TET2 mutations represent early genetic lesions as they had already been detected in haematopoietic precursor cells of AITL patients. We show by analysis of whole-tissue sections and microdissected PD1

PURPOSE The purpose of the present study was to examine the relationship between the serum levels of soluble CD 30 (S-sCD 30), the Hodgkin and Reed Sternberg (HRS) cell density and the macroscopic tumour burden in untreated patients with Hodgkin's disease (HD). MATERIALS AND METHODS In 126 untreated patients with HD diagnosed between 1979-1991, (79 males and 47 females, median age 33 years) S-sCD 30 was measured using frozen serum samples. The number of HRS cells (the HRS cell density) was counted in 10 high-power vision fields. The macroscopic tumour volume was estimated in 70 patients in stages I and II by counting the number of involved sites and scoring them according to size. RESULTS Soluble CD 30 was detected in the sera of all patients. The levels were significantly higher in patients with high HRS cell density, high macroscopic tumour burden, stages III-IV, B symptoms and bulky disease. Patients with high S-sCD 30 had a significantly poorer DFS (p < 0.05) and survival (p < 0.001). High HRS cell density correlated to large macroscopic tumour burden, stage IV disease and B-symptoms. Patients with the highest HRS cell density had a significantly poorer disease-free survival (DFS) (p < 0.01) and survival (p < 0.01). In a multivariate analysis, S-sCD 30 was more important as regards prognosis than HRS cell density. CONCLUSIONS Serum levels of sCD 30 are probably a measurement of tumour burden in HD and are also strongly related to the prognosis. A high number of HRS cells correlated to an extensive spread HD and also to prognosis.

Diffuse large B-cell lymphoma (DLBCL) is one of the most common and aggressive types of B-cell lymphoma. Deregulation of proto-oncogene expression after a translocation, most notably to the immunoglobulin heavy-chain locus (IGH), is one of the hallmarks of DLBCL. Using whole-genome sequencing analysis, we have identified the PD-L1/PD-L2 locus as a recurrent translocation partner for IGH in DLBCL. PIM1 and TP63 were also identified as novel translocation partners for PD-L1/PD-L2 Fluorescence in situ hybridization was furthermore used to rapidly screen an expanded DLBCL cohort. Collectively, a subset of samples was found to be affected by gains (12%), amplifications (3%), and translocations (4%) of the PD-L1/PD-L2 locus. RNA sequencing data coupled with immunohistochemistry revealed that these cytogenetic alterations correlated with increased expression of PD-L1 but not of PD-L2 Moreover, cytogenetic alterations affecting the PD-L1/PD-L2 locus were more frequently observed in the non-germinal center B cell-like (non-GCB) subtype of DLBCL. These findings demonstrate the genetic basis of PD-L1 overexpression in DLBCL and suggest that treatments targeting the PD-1-PD-L1/PD-L2 axis might benefit DLBCL patients, especially those belonging to the more aggressive non-GCB subtype.

In recent decades, the prognosis of Mantle Cell Lymphoma (MCL) has been significantly improved by intensified first-line regimens containing cytarabine, rituximab and consolidation with high-dose-therapy and autologous stem cell transplantation. One such strategy is the Nordic MCL2 regimen, developed by the Nordic Lymphoma Group. We here present the 15-year updated results of the Nordic MCL2 study after a median follow-up of 114years: For all patients on an intent-to-treat basis, the median overall and progression-free survival was 127 and 85years, respectively. The MCL International Prognostic Index (MIPI), biological MIPI, including Ki67 expression (MIPI-B) and the MIPI-B including mIR-18b expression (MIPI-B-miR), in particular, significantly divided patients into distinct risk groups. Despite very long response durations of the low and intermediate risk groups, we observed a continuous pattern of relapse and the survival curves never reached a plateau. In conclusion, despite half of the patients being still alive and 40% in first remission after more than 12years, we still see an excess disease-related mortality, even among patients experiencing long remissions. Even though we consider the Nordic regimen as a very good choice of regimen, we recommend inclusion in prospective studies to explore the benefit of novel agents in the frontline treatment of MCL.

Objective Patients with rheumatoid arthritis (RA) are at increased risk of malignant lymphomas with a strong correlation with RA disease severity. Given the changes in RA therapy over recent decades, this study was undertaken to assess whether lymphoma risk remains increased, and if so, to explore risk predictors and lymphoma subtypes. Methods We identified 12,656 cases of incident RA in the Swedish Rheumatology Quality Register 1997-2012 and obtained information on therapy and inflammatory activity during the first year after diagnosis. Each patient was matched to 10 population comparator subjects. Through linkage to the Swedish Cancer Register, lymphomas, including subtypes, were identified. We assessed hazard ratios (HRs) using Cox regression. Results Overall, the HR for lymphoma was increased in RA, to 1.6 (95% confidence interval [95% CI] 1.2-2.1). Taking RA duration into account, risks did not appear to have declined over successive calendar years of RA diagnosis. Neither use of methotrexate the first year after RA diagnosis nor ever use of tumor necrosis factor inhibitors (TNFi) increased lymphoma risk (HR 0.9 [95% CI 0.4-1.9]). Use of oral corticosteroids the first year after RA diagnosis was associated with a reduced risk (HR 0.5 [95% CI 0.3-0.9]). Inflammatory activity during the first year after RA diagnosis did not predict future lymphoma risk. Chronic lymphocytic leukemia occurred less frequently, and Hodgkin's lymphoma occurred more frequently, in RA patients than in the general population. Conclusion The average lymphoma risk in recently diagnosed RA is similar in magnitude to that reported in historical cohorts. Standard antirheumatic treatment including TNFi did not predict future lymphoma risk. Distribution of lymphoma subtypes warrants further investigation.

For elderly patients with mantle cell lymphoma (MCL), there is no defined standard therapy. In this multicenter, open-label phase 1/2 trial, we evaluated the addition of lenalidomide (LEN) to rituximab-bendamustine (R-B) as first-line treatment for elderly patients with MCL. Patients >65 years with untreated MCL, stages II-IV were eligible for inclusion. Primary end points were maximally tolerable dose (MTD) of LEN and progression-free survival (PFS). Patients received 6 cycles every four weeks of L-B-R (L D1-14, B 90 mg/m2 IV, days 1-2 and R 375 mg/m2 IV, day 1) followed by single LEN (days 1-21, every four weeks, cycles 7-13). Fifty-one patients (median age 71 years) were enrolled from 2009 to 2013. In phase 1, the MTD of LEN was defined as 10 mg in cycles 2 through 6, and omitted in cycle 1. After 6 cycles, the complete remission rate (CRR) was 64%, and 36% were MRD negative. At a median follow-up time of 31 months, median PFS was 42 months and 3-year overall survival was 73%. Infection was the most common nonhematologic grade 3 to 5 event and occurred in 21 (42%) patients. Opportunistic infections occurred in 3 patients: 2 Pneumocystis carinii pneumonia and 1 cytomegalovirus retinitis. Second primary malignancies (SPM) were observed in 8 patients (16%). LEN could safely be combined with R-B when added from the second cycle in patients with MCL, and was associated with a high rate of CR and molecular remission. However, we observed a high degree of severe infections and an unexpected high number of SPMs, which may limit its use. This trial is registered at www.Clinicaltrials.gov as #NCT00963534.

Background: IgG4-related disease (IgG4-RD) is a recently recognized fibro-inflammatory disorder, which may affect many organs, and often comes to clinical attention due to tumor-like organ swelling or is identified incidentally by specific biopsy findings. Typical histopathology of IgG4-RD is lymphoplasmacytic infiltration rich in IgG4 + plasma cells (PCs), storiform fibrosis, and obliterative phlebitis. Patients with sicca symptoms can be misdiagnosed as primary Sjögren’s syndrome (pSS) instead of IgG4-RD because of clinical and histopathological similarities. Moreover, an association with lymphoma development is described in both diseases. This study investigated signs of IgG4-RD in a population-based cohort of patients diagnosed with pSS complicated by lymphoma. Methods: Patients with pSS and lymphoma diagnoses and available lymphoma specimens were identified by linkage with the Swedish Patient Register 1964–2007 and the Cancer Register 1990–2007 (n = 79). Clinical data and lymphomas were reviewed and the diagnoses evaluated. All lymphoma tissues and available minor salivary gland biopsies (n = 11) were immunostained for IgG4 + PCs and evaluated for other histopathological signs of IgG4-RD. In a case with specific findings of IgG4-RD, other available tissue specimens of the same patient were investigated for IgG4-RD. Results: Only one patient of 79 (1.3%) had >10 IgG4 + PCs/high power field (HPF) in the lymphoma tissue, an unspecified low-grade B-cell lymphoma localized in the submandibular gland. This patient also had other histopathological features of IgG4-RD in the lymphoma and a surgical lung biopsy taken five years before lymphoma diagnosis and, therefore, fulfilled the criteria for IgG4-RD. Occasional IgG4 + PCs (Conclusion: Histopathological findings of IgG4-RD may co-exist with low malignant B-cell lymphoma in patients with initially suspected pSS and may be associated with an underlying IgG4-RD.

In chronic lymphocytic leukemia (CLL), the microenvironment influences gene expression patterns; however, knowledge is limited regarding the extent to which methylation changes with time and exposure to specific microenvironments. Using high-resolution 450K arrays, we provide the most comprehensive DNA methylation study of CLL to date, analyzing paired diagnostic/follow-up samples from IGHV-mutated/untreated and IGHV-unmutated/treated patients (n=36) and patient-matched peripheral blood and lymph node samples (n=20). On an unprecedented scale, we revealed 2239 differentially methylated CpG sites between IGHV-mutated and unmutated patients, with the majority of sites positioned outside annotated CpG islands. Intriguingly, CLL prognostic genes (for example, CLLU1, LPL, ZAP70 and NOTCH1), epigenetic regulator (for example, HDAC9, HDAC4 and DNMT3B), B-cell signaling (for example, IBTK) and numerous TGF-β and NF-κB/TNF pathway genes were alternatively methylated between subgroups. Contrary, DNA methylation over time was deemed rather stable with few recurrent changes noted within subgroups. Although a larger number of non-recurrent changes were identified among IGHV-unmutated relative to mutated cases over time, these equated to a low global change. Similarly, few changes were identified between compartment cases. Altogether, we reveal CLL subgroups to display unique methylation profiles and unveil methylation as relatively stable over time and similar within different CLL compartments, implying aberrant methylation as an early leukemogenic event.

Mantle cell lymphoma (MCL) is a heterogenic non-Hodgkin lymphoma entity, with a median survival of about 5 years. In 2008 we reported the early - based on the median observation time of 4 years - results of the Nordic Lymphoma Group MCL2 study of frontline intensive induction immunochemotherapy and autologous stem cell transplantation (ASCT), with more than 60% event-free survival at 5 years, and no subsequent relapses reported. Here we present an update after a median observation time of 6·5 years. The overall results are still excellent, with median overall survival and response duration longer than 10 years, and a median event-free survival of 7·4 years. However, six patients have now progressed later than 5 years after end of treatment. The international MCL Prognostic Index (MIPI) and Ki-67-expression were the only independent prognostic factors. Subdivided by the MIPI-Biological Index (MIPI + Ki-67, MIPI-B), more than 70% of patients with low-intermediate MIPI-B were alive at 10 years, but only 23% of the patients with high MIPI-B. These results, although highly encouraging regarding the majority of the patients, underline the need of a risk-adapted treatment strategy for MCL. The study was registered at www.isrctn.org as ISRCTN 87866680.

B cells from Cernunnos-deficient patients contain aberrant class switch recombination junctions, and a dominant-negative Cernunnos mutation was detected in a diffuse large B cell lymphoma sample., Cernunnos is involved in the nonhomologous end-joining (NHEJ) process during DNA double-strand break (DSB) repair. Here, we studied immunoglobulin (Ig) class switch recombination (CSR), a physiological process which relies on proper repair of the DSBs, in B cells from Cernunnos-deficient patients. The pattern of in vivo generated CSR junctions is altered in these cells, with unusually long microhomologies and a lack of direct end-joining. The CSR junctions from Cernunnos-deficient patients largely resemble those from patients lacking DNA ligase IV, Artemis, or ATM, suggesting that these factors are involved in the same end-joining pathway during CSR. By screening 269 mature B cell lymphoma biopsies, we also identified a somatic missense Cernunnos mutation in a diffuse large B cell lymphoma sample. This mutation has a dominant-negative effect on joining of a subset of DNA ends in an in vitro NHEJ assay. Translocations involving both Ig heavy chain loci and clonal-like, dynamic IgA switching activities were observed in this tumor. Collectively, our results suggest a link between defects in the Cernunnos-dependent NHEJ pathway and aberrant CSR or switch translocations during the development of B cell malignancies.

Background and aim of the study Primary mediastinal B-cell lymphoma (PMBL) is an entity of aggressive B-cell lymphoma that is clinically and biologically distinct from the other molecular subtypes of diffuse large B-cell lymphoma (DLBCL). We recently detected by Whole exome sequencing a recurrent point mutation in the XPO1 (exportin 1) gene (also referred to as chromosome region maintenance 1; CRM1), which resulted in the Glu571Lys (p.E571K) missense substitution in 2 refractory/relapsed PMBL (Dubois et al., ICML 2015; Mareschal et al. AACR 2015). XPO1 is a member of the Karyopherin-b superfamily of nuclear transport proteins. XPO1 mediates the nuclear export of numerous RNAs and cellular regulatory proteins, including tumor suppressor proteins. This mutation is in the hydrophobic groove of XPO1 that binds to the leucine-rich nuclear export signal (NES) of cargo proteins. In this study, we investigated the prevalence, specificity, and biological / clinical relevance of XPO1 mutations in PMBL. Patients and methods High-throughput targeted or Sanger sequencing of 117 PMBL patients and 3 PMBL cell lines were performed. PMBL cases were defined either molecularly by gene expression profile (mPMBL cohort) or by standard histological method (hPMBL cohort) and enrolled in various LYSA (LYmphoma Study Association) clinical trials. To assess the frequency and specificity of XPO1 mutations, cases of classical Hodgkin lymphoma (cHL) and primary mediastinal grey zone lymphoma (MGZL) were analysed. Cell experiments were performed to assess the impact of the E571 mutation on the activity of selective inhibitor of nuclear export (SINE) molecules. Results XPO1 mutations were present in 28/117 (24%) PMBL cases but were rare in cHL cases (1/19, 5%) and absent from MGZL cases (0/20). A higher prevalence (50%) of the recurrent codon 571 variant (p.E571K) was observed in PMBL cases defined by gene expression profiling (n = 32), as compared to hPMBL cases (n = 85, 13%). No difference in age, International Prognostic Index (IPI) or bulky mass was observed between the PMBL patients harboring mutant and wild-type XPO1 in the overall cohort whereas a female predominance was noticed in the mPMBL cohort. Based on a median follow-up duration of 42 months, XPO1 mutant patients exhibited significantly decreased PFS (3y PFS = 74% [CI95% 55-100]) compared to wild-type patients (3y PFS = 94% [CI95% 83-100], p=0.049) in the mPMBL cohort. In 4/4 tested cases, the E571K variant was also detected in cell-free circulating plasmatic DNA, suggesting that the mutation can be used as a biomarker at the time of diagnosis and during follow-up. Importantly, the E571K variant was detected as a heterozygous mutation in MedB-1, a PMBL-derived cell line, whereas the two other PMBL cell lines tested, Karpas1106 and U-2940, did not display any variants in XPO1 exon 15. KPT-185, the SINE compound that blocks XPO1-dependent nuclear export, induced a dose-dependent decrease in cell proliferation and increased cell death in the PMBL cell lines harbouring wild type or mutated alleles. To test directly if XPO1 mutation from E571 to E571K alters XPO1 inhibition by SINE compounds, the mutated protein was tested in vitro. The E571XPO1 mutated allele was transiently transfected into osteosarcoma U2OS cells which stably express the fluorescently labelled XPO1 cargo REV. Cells were treated with the clinical SINE compound selinexor, which is currently in phase I/II clinical trials and nuclear localization of REV-GFP was analysed in red transfected cells. The results showed that the nuclear export of the mutated XPO1 protein was inhibited by selinexor similarly to the wild-type XPO1 protein (Figure 1). Conclusion Although the oncogenic properties of XPO1 mutations remain to be determined, their recurrent selection in PMBL strongly supports their involvement in the pathogenesis of this curable aggressive B-cell lymphoma. XPO1 mutations were primarily observed in young female patients who displayed a typical PMBL molecular signature. The E571K XPO1 mutation represents a novel hallmark of PMBL but does not seem to interfere with SINE activity. Rev-GFP (green fluorescent) expressing U2OS cells were transfected with wild type XPO1-RFP (red fluorescent protein), XPO1-C528S-RFP, XPO1-E571K-mCherry, and XPO1-E571G-mCherry. The cells were then treated with 1µM KPT-330 for 8 hours. Figure 1. Rev-GFP expressing U2OS cells transfected with XPO1 variants. Figure 1. Rev-GFP expressing U2OS cells transfected with XPO1 variants. Disclosures Landesman: Karyopharm Therapeutics: Employment. Senapedis:Karyopharm Therapeutics, Inc.: Employment, Patents & Royalties. Argueta:Karyopharm Therapeutics: Employment. Milpied:Celgene: Honoraria, Research Funding.